1. Field of the Invention
The present invention relates to a battery and, more particularly, to a device and method for determining the charge capacity of a battery within predetermined quantitative ranges and displaying the determined value using 7-segment light emitting diode (LED) display modules.
2. Description of the Related Art
A typical device for indicating the capacity (or voltage) of a battery displays one or two colored LEDs to indicate the charge status (i.e., voltage level) of the battery. With such a device a user cannot know the present capacity of the battery. Accordingly, the user cannot accurately anticipate when the battery will become exhausted or, if the battery is being charged, estimate the time required to fully charge it.
Various approaches have been proposed to address the problem of providing a quantitative indication of the existing charge in a battery. For example, U.S. Pat. No. 4,020,414 shows a device with a plurality of comparators and an indicator connected to the output of each comparator. The comparators indicate the battery voltage level relative to different reference levels, and thus the device provides an indication of the battery's remaining charge. But the design of this system may require relatively expensive integrated circuits to implement and does not allow easy modification to enhance existing functions or to add new ones.
U.S. Pat. No. 5,126,675, on the other hand, proposes an alternative solution using diodes and LEDs. The disclosed system here does not involve sophisticated comparator circuitry and still provides a quantitative indication of remaining battery capacity. On the other hand, it requires a large number of discrete components in an arrangement that makes modification or addition of functions awkward. This circuit also measures battery voltage by an indirect method (equivalent internal resistance) and generates an analog indicating output signal not easily adapted to digital display means.
I have therefore found that a need exists for an improved battery charge indicating device and method. Such an invention would provide a quantitative indication of remaining charge in a battery but would have a flexible design readily adaptable to improvement of and addition to its functional capabilities without requiring expensive and delicate integrated components. This system would also include detection means with output readily amenable to digital processing and would provide a flexible and easily-read display means. It also desirably would allow implementation with inexpensive, standard components or in configurations suitable for harsh or unusual use environments.